Use Of Phosphate Solubilizing Bacteria Research Articles

Endophytic Bacillus vallismortis and Bacillus tequilensis bacteria isolated from medicinal plants enhance phosphorus acquisition and fortify Brassica napus L. vegetative growth and metabolic content.

Phosphorus fertilization imposes critical limitations on crop productivity and soil health. The aim of the present work is to explore the potential of two phosphate solubilizing bacteria (PSB) species in phosphorus supplementation of canola (Brassica napus L.). Out of 38 bacterial isolates obtained from nine medicinal plants, two bacterial strains (20P and 28P) were proved as the most potent for the in-vitro tricalcium phosphate solubilization test. These isolates verified their activity toward different enzymes as nitrogenase and alkaline phosphatase. Also, 20P and 28P gave a high amount of indole-3-acetic acid, 34.16 μg/ml and 35.20 μg/ml, respectively, and were positive for siderophores production as they detected moderate affinity for iron chelation. Molecular identification confirmed that strain 20P was Bacillus vallismortis and strain 28P was Bacillus tequilensis. A pot experiment was conducted to study the effect of four different phosphorus concentrations (0%, 50%, 75%, and 100% P) each alone and/or in combination with B. vallismortis, B. tequilensis, or both bacterial isolates on the vegetative growth and some physiological parameters of canola. The combined treatment of 50% phosphorus + (B. vallismortis + B. tequilensis) was generally the most effective with respect to shoot height, shoot dry mass, leaf area, photosynthetic pigment fractions, total sugar content, and accumulated NPK content. In contrast, the rhizosphere pH reached the minimum value under the same treatment. These findings highlighted the potential use of PSB (B. vallismortis and B. tequilensis) along with phosphorus fertilization as a safe sustainable tactic.

Mitigating the effects of water-deficit stress on potato growth and photosynthesis using mycorrhizal fungi and phosphate-solubilizing bacteria

AbstractBiofertilizers, such as arbuscular mycorrhiza fungi and phosphate-solubilizing bacteria (PSB), have been reported to enhance plant growth under water stress conditions. This study aimed to investigate the effect of different biofertilizers on potato photosynthesis and growth under water deficit stress. The experiment was conducted over two crop years (2019 and 2020) using a randomized complete block design with three replications. Four irrigation intervals (70, 90, 110 and 130 mm of cumulative evaporation) and six biofertilizer treatments (PSB, Funneliformis mosseae [FM], Rhizoglomus fasciculatum [RF], PSB + FM, PSB + RF and no use) were applied. Severe moisture stress (130 mm evaporation) compared to no stress (70 mm evaporation) increased substomatal carbon dioxide concentration. The application of biofertilizers improved tuber yield under severe moisture stress, with FM showing the highest increase (62.9%), followed by RF (59.8%) and PSB (48.4%). The use of PSB along with mycorrhizae led to a significant decrease in mycorrhizal colonization percentage at all irrigation levels. The highest percentage of colonization and net photosynthesis was obtained from the application of both mycorrhizal species under irrigation conditions after 70 mm of evaporation. The application of PSB alone resulted in a 14.6% increase in the transpiration rate, additionally, the use of mycorrhiza led to an 18.7% increase in stomatal conductivity compared to no-biofertilizer. The results suggest that the simultaneous use of PSB and mycorrhizae can be effective in mild moisture stress, but in severe moisture stress, the use of mycorrhizal species alone is more effective.

Application of Bacillus spp. Phosphate-Solubilizing Bacteria Improves Common Bean Production Compared to Conventional Fertilization.

The use of phosphate-solubilizing bacteria (PSB) can be a sustainable strategy to increase phosphorus availability and promote satisfactory crop yields. The objective of this study was to evaluate whether inoculation with PSB in common bean increases (i) growth, (ii) nutrition, (iii) yield, and (iv) grain quality, and (v) reduces the chemical phosphorus application dose to obtain maximum yields. The experiment was conducted in an Oxisol using a randomized block design in a 4 × 4 factorial scheme, with four replicates, using the cultivar IAC 2051. The first factor was four doses of P2O5 (0, 20, 40 and 60 kg ha-1), and the second factor was four doses of PSB (0, 100, 200 and 300 mL ha-1). For leaf area and leaf chlorophyll content, the association of PSB inoculation with a P2O5 dose of 40 kg ha-1 promoted the best conditions for the common bean. P2O5 application increased yield by 79 kg ha-1 for each 10 kg ha-1 added. PSB inoculation at a dose of 192 mL ha-1 promoted P export of 15.3 kg ha-1, and the PSB dose of 159 mL ha-1 increased yield by 389 kg ha-1 (12%) compared to the control. Grain quality remained within the standards required by the consumer market, being little affected by the treatments. Improvements in common bean growth and nutritional and physiological status promoted by P2O5 application and PSB were essential in increasing yield, so these are sustainable production strategies.

Potential Use of Phosphate-Solubilizing Bacteria in Soybean Culture

Using microorganisms to enhance crop productivity is an active and increasing field of research, which encompasses the productive, environmental, and economic aspects of agricultural production to obtain high-quality crops with a reduction in the need for fertilizers. Among the nutrients necessary for plant growth, phosphorous is problematic due to its low availability and its susceptibility to convert into non-labile forms. In this regard, phosphate-solubilizing bacteria (PSB) can be an interesting tool to improve phosphorous availability and to reduce the requirements of phosphate fertilizers. This work aimed to evaluate the potential use of phosphate-solubilizing bacteria in the supply of phosphorus and soybean development. This study was conducted in the 2019/2020 and 2020/2021 harvests. The experimental design was in randomized blocks, containing seven treatments and six replicates. The treatments consisted of five doses of phosphate fertilization, using triple superphosphate fertilizer, associated with the application of Bacillus subtilis and Bacillus megaterium bacteria, and two treatments, with and without the use of phosphorous fertilizer and without the use of an inoculant. Plant tissue nutrients and biometric and productive parameters of the crop were assessed. According to the observed results, applying PSB associated with phosphate fertilization and phosphate fertilization alone did not influence soybean’s nutritional, biometric, and productive parameters in the two harvests. Thus, the application of B. subtilis and B. megaterium, either associated or not associated with phosphate fertilization, does not contribute to the nutrition, development, and yield of soybean crops in soil with a naturally low P content, considering the climatic and soil conditions of the study.

Phosphate Solubilizing Bacteria: A potential biotic component for solubilizing phosphate in soil and its application as Biofertilizer: A Review

The number of populations is increasing day by day. As populations no is being increased, the demand of food is also increasing simultaneously. Therefore, it’s easy to understand that no. of population growing is directly proportional to the demand of food. To increase the yield of food crops a large amount of chemical fertilizers is used every year. But certainly, these chemical fertilizers can cause long term damage to environment as well as on the bodies of those who will consume the grains also. In that case definitely we have to think some alternatives of chemical or artificial fertilizers. In addition, in spite of presence of sufficient amount of phosphate in soil, plant can’t get the access of phosphate as it forms complex with either inorganic metal ion or various organic compounds. On that note scientists and researchers have studied some microorganisms which can play very significant role in this critical situation. This microorganism live in rhizosphere region of plant and can increase soil fertility by solubilizing phosphate and also help in the development of plant. These are known as Phosphate Solubilizing Bacteria (PSB). This review discussed the different species of PSB, the mechanisms they follow to solubilize phosphate, their role in plant development. This research review also focuses on use of phosphate solubilizing bacteria for sustainable agricultural purpose.

Innovative Rhizosphere-Based Enrichment under P-Limitation Selects for Bacterial Isolates with High-Performance P-Solubilizing Traits.

The use of phosphate solubilizing bacteria (PSB) as inoculants for the rhizosphere is a well-known strategy to mitigate P-deficiency in plants. However, despite the multiple modes of action to render P available for plants, PSB often fail to deliver in the field as their selection is often based on a single P-solubilizing trait assessed in vitro. Anticipating these shortcomings, we screened 250 isolates originating from rhizosphere-based enriched consortia for the main in vitro P-solubilizing traits, and subsequently grouped the isolates through trait-based HCPC (hierarchical clustering on principal components). Representative isolates of each cluster were tested in an in planta experiment to compare their in vitro P-solubilizing traits with their in planta performance under conditions of P-deprivation. Our data convincingly show that bacterial consortia capable to mitigate P-deficiency in planta were enriched in bacterial isolates that had multiple P-solubilizing traits in vitro and that had the capacity to mitigate plant P-stress in planta under P-deprived conditions. Furthermore, although it was assumed that bacteria that looked promising in vitro would also have a positive effect in planta, our data show that this was not always the case. Opposite, lack of performance in vitro did not automatically result in a lack of performance in planta. These results corroborate the strength of the previously described in planta-based enrichment and selection technique for the isolation of highly efficient rhizosphere competent PSB. IMPORTANCE With the growing awareness on the ecological impact of chemical phosphate fertilizers, research concerning the use of phosphate solubilizing bacteria (PSB) as a sustainable alternative for, or addition to these fertilizers is of paramount importance. In previous research, we successfully implemented a plant-based enrichment technique for PSB, which simultaneously selected for the rhizosphere competence and phosphate solubilizing characteristics of bacterial suspensions. Current research follows up on our previous findings, whereas we screened 250 rhizobacteria for their P-solubilizing traits and were able to substantiate the results obtained from the enriched suspensions at a single-isolate level. With this research, we aim for a paradigm shift toward the plant-based selection of PSB, which is a more holistic approach compared to the plate-based methods. We emphasize the strength of the previously described plant-based enrichment and selection technique for the isolation of highly efficient and diverse PSB.

Free and Encapsulated Phosphate-Solubilizing Bacteria for the Enhanced Dissolution of Swine Wastewater-Derived Struvite—An Attractive Approach for Green Phosphorus Fertilizer

Struvite and hydroxyapatite are byproducts of phosphorus removal from wastewater that can be used as phosphate fertilizers. Due to their low water solubility, especially in alkaline soils, their use is currently limited. The use of phosphate-solubilizing bacteria to enhance the dissolution of struvite and hydroxyapatite could be an attractive solution for expanding their use, but literature reports on this are limited. In this study, Arthrobacter sp. (TBRC 5201), Azotobacter vinelandii (TBRC 7231), and Bacillus megaterium (TBRC 1396) were evaluated for their ability to dissolve struvite and hydroxyapatite on agar media with struvite or hydroxyapatite as the sole source of phosphorus. Only B. megaterium (TBRC 1396) was able to use struvite and hydroxyapatite for growth. After 14 d of incubation in liquid medium, B. megaterium (TBRC 1396) dissolved phosphorus from struvite up to 835.45 ± 11.76 mg P/l compared with 196.08 ± 3.92 mg P/l in a control without cells, whereas the dissolution of hydroxyapatite by B. megaterium was minimal. B. megaterium (TBRC 1396) was also capable of dissolving phosphorus from swine wastewater-derived struvite. Both free cells and alginate-encapsulated cells of B. megaterium (TBRC 1396) were able to rapidly dissolve phosphorus from swine wastewater-derived struvite, resulting in soluble phosphorus concentrations that reached 400 mg P/l within 2 days, compared with those without cells that required 12 days. In conclusion, the application of struvite with phosphate-solubilizing bacteria is a promising tool for green sustainable agriculture.

Improvement of phosphorus uptake, phosphorus use efficiency, and grain yield of upland rice (Oryza sativa L.) in response to phosphate-solubilizing bacteria blended with phosphorus fertilizer

Phosphorus (P) limitation in soil is a major concern for crop productivity. However, the use of chemical fertilizer is hazardous to the environment and costly. Therefore, the use of phosphate-solubilizing bacteria (PSB) is an eco-friendly approach for a sustainable agricultural system. In the present study, a field trial was conducted for two consecutive years to study the effects of three PSB strains isolated, Bacillus licheniformis, Pantoea dispersa, and Staphylococcus sp., with different P fertilizer rates on P uptake, P use efficiency (PUE), and grain yield of rice. The activities of soil enzymes were also studied in relation to PSB treatments. Comparative analysis of the yield and biochemical parameters revealed that inoculation of PSB consortium could reduce almost 50% of the recommended P dose in rice cultivation. Three PSB strains in combination with 50% P dose was most effective and showed the highest increases in P uptake and PUE as compared to the uninoculated control. Moreover, the PSB consortium combined with 50% P dose contributed to 50.58% and 35.64% yield increases compared to the uninoculated control for 2018 and 2019, respectively. Significant increases in the activities of soil dehydrogenase, alkaline phosphatase, and acid phosphatase were also recorded under PSB treatment.

Isolation and identification of phosphate solubilizing bacteria from the rhizosphere of rice in organic and non-organic rice fields in Sukoharjo District, Indonesia

Abstract. Purwanti D, Setyaningsih R, Susilowati A. 2019. Isolation and identification of phosphate solubilizing bacteria from the rhizosphere of rice in organic and non-organic rice fields in Sukoharjo District, Indonesia. Bonorowo Wetlands 9: 108-115. One of the essential nutrients in the soil is phosphate. Phosphate fertilization is often inefficient because phosphate is bound and difficult for plants to absorb. The use of phosphate solubilizing bacteria (PSB) can be used as an alternative to the availability of P in the soil. This study aimed to obtain PSB isolates with high phosphate solubilization ability and identify these PSB isolates molecularly. Soil samples were taken from organic and non-organic rice (Oryza sativa L.) fields in Sukoharjo, Central Java, Indonesia, namely Grogol Village, Menuran Village, and Pondok Village. The research activity was carried out in several stages: isolation of PSB on Pikovskaya medium, characterization and testing of PSB in dissolving P, and Gram staining. PSB colonies with a phosphate solubilization index and showed different colony colors were taken, and then DNA was isolated. DNA isolation was carried out by extraction method using a DNA extraction kit. The gene encoding 16S rRNA amplified the obtained DNA samples. Sequencing was carried out using a genetic analyzer. Data analysis by comparing sequence data on the BLASTN program. Based on the isolation of rhizosphere samples from organic paddy fields, 14 isolates of PSB were obtained, and ten isolates of non-organic paddy were PSB. P13, P1, Q7, and Q8 isolates had the highest P solubilization ability with dissolution index (IP), namely 3.35, 2.13, 1.82, and 1.47. The 16S rRNA gene sequence analysis showed that isolates P1 and P13 had 99% similarity to Acinetobacter sp. ADP1 strain. The isolate Q7 had a 96% similarity with the genus Clavibacter strain NCPPB 382, ??while Q8 had a 99% similarity with Pseudomonas aeruginosa strain PAO1.

Organic amendment plus inoculum drivers: Who drives more P nutrition for wheat plant fitness in small duration soil experiment.

Functioning of ecosystems depends on the nutrient dynamics across trophic levels, largely mediated by microbial interactions in the soil food web. The present study investigated the use of phosphate solubilizing bacteria (PSB) and poultry manure (PM) for maintaining labile P in the soil for an extensive fertility enhancement and as a substitution of chemical fertilizers. Based on the different P solubilizing capabilities of Bacillus and Pseudomonas, a quadruple consortium of Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis and Pseudomonas fluorescens, and their grazer nematodes (soil free living) supplemented with PM were studied. This study was carried out on the trophic levels of soil communities to assess the growth and availability of P to the wheat plants. Experiment was performed for 90 days. Comparing the unamended and amended predator results showed that nematode addition beyond bacterial treatment substantially increased the net available P by ≈2 times, and alkaline phosphatase (ALP) activity by 3.3 times. These results demonstrated the nematodes association with increasing nutrient availability or P mineralization. The interactive effect of PM as substrate and biological drivers was more noticeable on plant dry biomass (1.6 times) and plant P concentration (3.5times) compared to the similar unamended treatment. It is concluded that the biological drivers significantly enhanced the soil ALP and available P while the substrate and biological drivers enhanced dry biomass and plant P concentration. Bacterivore nematodes enhanced the effect of PSB for P mineralization via microbial loop and could be used for the enhancement of wheat production.

Integrated Use of Biofertlizers with Organic and Inorganic Phosphorus Sources Improve Dry Matter Partitioning and Yield of Hybrid Maize

ABSTRACT Phosphorus (P) unavailability and lack of organic matter in calcareous soils under semiarid climates are major reasons for low maize productivity grown in these conditions. The hypothesis was tested that integrated use of biofertilizers (BF) and P-sources could improve dry matter (DM) partitioning and yield of hybrid maize (CS-200) in the semiarid climate of Peshawar. A field trial was conducted to investigate the impact of two BF-sources, and eight organic and inorganic P-sources combinations (P) on DM partitioning, yield, and yield components of hybrid maize. The research was conducted at the Agronomy Research Farm of The University of Agriculture Peshawar, during summer 2017. Experiment was laid out in randomized complete block design with split plot arrangement, using four replications. Combination of inorganic-P [single super phosphate (SSP) and rock phosphate (RP)] and organic-P (compost and biochar) sources was used as factor-A, and BF [Phosphate Solubilizing Bacteria (PSB) and Trichoderma (TD)] as factor-B. Phosphorus was applied at the uniform rate of 120 kg ha−1 from different sources (08 treatments). The results revealed that P sources and BF had significantly affected all parameters under study. As compared with TD, application of PSB had significantly increased total plant dry weight (TDW), leaf dry weight (LDW), cob dry weight (CDW), husks dry weigh (HDW), stem dry weight (SDW), and roots dry weight (RDW) at both silking and physiological maturity. The highest ear length (EL), more number of grains per row (NGPR), number of rows per ear (NRPE), number of grains per ear (NGPE), heavy thousand grains weight (TGW), higher total biological yield above ground (BY), grain yield (GY), stover yield (SY), harvest index (HI), and shelling percentage (SP) were obtained with application of PSB over TD. As compared with sole biochar (T3), application of organic-P in the form of sole compost (T4) had significantly increased plant TDW (188.8 g & 312.9 g), LDW (34.3 g & 29.0 g), CDW (41.9 g & 176.1 g), HDW (25.9 g & 21.7 g), SDW (85.4 g & 65.6 g), RDW (26.9 g & 15.2 g) at silking and physiological maturity, respectively. Significantly higher yields (GY, SY, BY, HI & SP) and yield components (EL, NGPE, NRPE & TGW) were recorded with sole compost application (T4) or combined application of compost + SSP (T6). Among all possible interactions of BF and treatments (2 x 8 = 16 combinations), the integrated use of PSB x T4, and PSB x T6 was found to the most beneficial combinations for improving DM partitioning, yield and yield components of hybrid maize in the study area. Interestingly, the integrated use of BF with RP (T7 & T8) had more positive effect on DM partitioning, yield and yield components of hybrid maize than sole application of RP (T2).

ФОСФАТСОЛЮБИЛИЗИРУЮЩИЕ БАКТЕРИИ РОДА PSEUDOMONAS И ЭФФЕКТИВНОСТЬ ИХ ПРИМЕНЕНИЯ ДЛЯ УВЕЛИЧЕНИЯ ДОСТУПНОСТИ ФОСФОРА

Phosphorus is the second most important element for plants after nitrogen. Fertilizers based on it, used to stimulate productivity, are inaccessible for most crops, which leads to their accumulation in the soil and environmental pollution. The use of phosphate-solubilizing bacteria increases the amount of phosphorus absorbed by plants. In most publications describing this group of bacteria, their effectiveness is assessed only in vitro by the halo zones formed on agar media with calcium orthophosphate. The aim of this study was to compare the solubilizing properties of bacteria of the genus Pseudomonas on a solid nutrient medium, as well as in sand and soil. It was shown that all studied cultures of microorganisms are capable of solubilizing insoluble phosphate in Pikovskaya's medium. The most active strains were Pseudomonas laurentiana ANT 56 and Pseudomonas sp. IB 182, isolated from the activated sludge of biological treatment facilities and arable soil, respectively. Experiments with the introduction of strains showed that the amount of mobile phosphorus in the sand increased 2.6-3.8 times in two weeks (in the control 1.2 times), while in the experiment with soil, a significant increase in the content of mobile phosphorus compared to the control was recorded only for the strain P . laurentiana ANT 17 (by 29.1%). It is assumed that the high solubilizing activity of the P. laurentiana ANT 17 strain may be due to the complex action of mechanisms of different nature, including the synthesis of indolyl-3-acetic acid and exopolysaccharide. The studies carried out make it possible to consider this bacterial strain as a promising object for creating on its basis a biological preparation for agricultural purposes.

Utilization of indigenous phosphate-solubilizing bacteria to optimize the use of coal fly ash for increasing available-P in an Ultisol

Coal fly ash (CFA) is a coal-burning by-product containing macro and micronutrients, and it is the potential material for improving available P in Ultisols. Phosphate-solubilizing bacteria (PSB) play a role in phosphorus solubilization. This study aimed at elucidating the potential use of phosphate-solubilizing bacteria to optimize the use of coal fly ash for increasing soil available P. This study was conducted in two stages, namely isolation of indigenous PSB from an Ultisol and application of the PSB and CFA to improve soil available P. Five indigenous PSB isolated from the soil had the ability to dissolve phosphate. Isolate B5 could dissolve 9.89 ppm P and had a 99.57% closeness to Pseudomonas stutzeri. The application of 20 and 40 t CFA ha-1 increased the soil pH by 4.2% and 7.2%, respectively. Increasing the dose of CFA decreased the content of available P by 50.6%. However, the combination of PSB and 20 t CFA ha-1 increased soil available P, plant growth, plant dry biomass, and P-uptake by plant.

Insight into the mechanisms of insoluble phosphate transformation driven by the interactions of compound microbes during composting.

Phosphate-solubilizing (PS) microbes are important to improve phosphorus availability and transformation of insoluble phosphate, e.g., rock phosphate (RP). The use of phosphate solubilizing bacteria (PSB) as inoculants have been proposed as an alternative to increase phosphate availability in RP and composting fertilizers. In this study, the effect of compound PSB coinoculation and single-strain inoculation on the transformation of insoluble phosphate were compared in a liquid medium incubation and RP-enriched composting. The goal of this study was to understand the possible mechanisms of insoluble phosphate transformation driven by the interactions of compound PS microbes during composting. The correlations between organic acids production, P-solubilization capacity and bacterial community with PSB inoculation were investigated in the RP-enriched composting by redundancy analysis (RDA) and structural equation models (SEM). Results showed that both single-strain and compound PSB inoculants had a high P-solubilization capacity in medium, but the proportion of Olsen P to total P in composts with inoculating compound PS microbes was 7% higher than that with single strain. PS inoculants could secrete different organic acids and lactic was the most abundant. However, RDA and SEM suggested that oxalic might play an important role on PS activity, inducing RP solubilization by changing pH during composting. Interaction between compound microbes could intensify the acidolysis process for insoluble P transformation compared to the single strain. Our findings help to understand the roles of complex microbial inoculants and regulate P availability of insoluble phosphate for the agricultural purposes.

Efficiency of phosphate-solubilizing bacteria to address phosphorus fixation in Takhli soil series: a case of sugarcane cultivation, Thailand

The efficiency test of phosphate-solubilizing bacteria (PSB) biofertilizer had two objectives: (i) to study the effect of the use of PSB on phosphate solubilization of the Takhli (Tk) soil series in soil columns and, (ii) to study their impact on sugarcane (cv. Lampang) cultivation in pots. PSB were identified and examined for phosphate-solubilizing activity on culture medium. In soil columns, the available phosphorus was analyzed from leached water. In pots, the yield and yield components of sugarcane were measured at age 12 months. The PSB belonged to the Bacillus group. The use of PSB at a rate of 64 g kg−1 in the Tk soil series produced the highest available phosphorus at 30.00 mg L−1 at 90 days under the soil column. PSB with chemical fertilizers according to soil analysis improved the yield and yield components of sugarcane with increasing rates of PSB. The maximum yield of sugarcane was produced with N:P:K chemical fertilizer (47:47:47 kg ha−1) with the PSB rate of 225 kg ha−1. Application of PSB can address the problem of phosphorus fixation in the Takhli soil series. Furthermore, the PSB had the ability to promote the yield and yield components of sugarcane cultivation in pots.

SORGHUM GENOTYPES RESPONSE TO INOCULATION WITH PHOSPHATE SOLUBILIZING BACTERIA

Sorghum bicolor adapts to phosphorus (P) deficient soils through mechanisms that contribute to its absorption and solubilization, including the association with microorganisms. The direct application of rock phosphate (RP) and the inoculation with phosphate solubilizing bacteria (PSB) is a sustainable alternative for P supply to the crops. The aim of this study was to evaluate the effect of PSB inoculation of two sorghum genotypes with different P responses (BR007 - efficient and responsive and SC283 - efficient and non-responsive), cultivated in soil fertilized with RP and triple superphosphate (TSP), in greenhouse and field experiments. The sorghum genotypes were inoculated separately with the Bacillus strains that are efficient in P solubilization, B116 and B70, and cultivated under different P fertilization sources (TSP, RP, ½TSP + ½RP). The results suggest that the inoculation response was dependent on sorghum genotype, P source and microbial strain. Inoculation of the genotype BR007 significantly increased root biomass and grain P content under greenhouse conditions, as well as yield and grain P content in field experiments, but no effect was observed on genotype SC283. The use of PSB as bioinoculants, in combination with RP, is a promising alternative to reduce the use of synthetic fertilizers, contributing to the sustainable sorghum production.

Role of Organic Materials and Phosphate Solubilizing Bacteria to Available Phosphate in Soil And Growth of Tomato Plant (Solanum lycopersicum)

Tomato plant ( Solanum lycopersicum ) is a horticultural plant that has high economic value. The demand for tomatoes per year is an average of 20%. In order to meet the demand for tomatoes, it is necessary to increase tomato production both in quality and quantity. This study aims to determine the effect of the use of phosphate solubilizing bacteria (BPF), the use of organic matter, and the effect of the interaction of phosphate solubilizing bacteria (BPF) and organic matter on soil pH, soil available P, the number of P solvent microbial populations and the growth of tomato plants. The design used in this study was a factorial Completely Randomized Design (CRD) consisting of 2 factors, namely the first factor was the concentration of Pseudomonas sp. which consists of 3 levels, namely without giving the bacteria Pseudomonas sp. (P0), giving the bacteria Pseudomonas sp. 10 ml (P1), and giving the bacteria Pseudomonas sp. 20 ml (P2). The second factor was the provision of organic material in the form of goat manure dosage consisting of 2 levels, namely without organic material (B0), and with organic material of 100 gr / polybag (P1). The parameters observed were plant height growth, number of leaves, shoot wet weight, crown dry weight, number of flowers, available soil P, soil pH, and the total population of soil P solubilizing microbes. The results showed that there was an interaction between the inoculum of Pseudomonas sp. and organic matter affects the growth of plant height, number of leaves, shoot wet weight, crown dry weight, number of flowers, available soil P, soil pH, and total soil P solvent microbes

Coupling Phosphate-Solubilizing Bacteria with Phosphorus Supplements Improve Maize Phosphorus Acquisition and Growth under Lime Induced Salinity Stress.

Global warming promotes soil calcification and salinization processes. As a result, soil phosphorus (P) is becoming deficient in arid and semiarid areas throughout the world. In this pot study, we evaluated the potential of phosphate-solubilizing bacteria (PSB) for enhancing the growth and P uptake in maize under varying levels of lime (4.8%, 10%, 15% and 20%) and additional P supplements (farmyard manure, poultry manure, single super phosphate and rock phosphate) added at the rate of 45 mg P2O5 kg−1. Inoculation and application of P as organic manures (Poultry and farm yard manures) improved maize growth and P uptake compared to the control and soils with P applied from mineral sources. Liming adversely affected crop growth, but the use of PSB and organic manure significantly neutralized this harmful effect. Mineral P sources combined with PSB were as effective as the organic sources alone. Furthermore, while single supper phosphate showed better results than Rock phosphate, the latter performed comparably upon PSB inoculation. Thus, PSB plus P application as organic manures is an eco-friendly option to improve crop growth and P nutrition in a calcareous soil under changing climate.

Exogenous phosphorus-solubilizing bacteria changed the rhizosphere microbial community indirectly.

Phosphate-solubilizing bacteria (PSB) have been widely used as biological fertilizer. However, its impact on the local microbial community has less been known. In this study, a mixture of PSB was inoculated into the tomato growth alone or combined with manure fertilizer. The growth parameter results showed that the combination use of PSB and compost could significantly increase the tomato growth and yield. The use of PSB could significantly increase pH, available phosphorus and several kinds of trace elements both in the rhizosphere and non-rhizosphere soil. The quantitative PCR and high-throughput sequencing results showed that the inoculated PSB did not become the dominant strains in the rhizosphere. However, the soil bacterial community structure was changed. The relative abundance of several indigenous bacteria, such as Pseudomonas, decreased, while the population of several bacteria, including Bacillus, Anaerolineaceae, Cytophagaceae, and Gemmationadaceae, increased. The redundancy analysis result showed that the soil properties had a great influence on the indigenous microbial community. In conclusion, the inoculated PSB could not colonize in the soil with a single inoculation. The PSB secreted small molecular organic acids to dissolve inorganic phosphorus and changed the soil properties, which changed the rhizosphere microbial community indirectly.

Isolation, Selection and Characterization of Root-Associated Rock Phosphate Solubilizing Bacteria in Moroccan Wheat (Triticum aestivum L.)

Phosphorus (P) is the most important macronutrient next to nitrogen for the growth and development of plants. But often unavailable for plants because of its high reactivity with many soil constituents. Thus, the use of phosphate solubilizing bacteria (PSBs) as biofertilizers seems to be an effective way to resolve the soluble phosphorus availability in soil. The present study was conducted to isolate and characterize rock PSB associated with the rhizosphere of wheat (Triticum aestivum L.) from fourteen different wheat-growing sites of Meknes region in Morocco. A total of one hundred ninety-eight (198) rock PSBs were isolated employing NBRIP medium amended with rock phosphate (RP), out of which five strains (A17, A81, B26, B106, and B107) were selected for their strong ability to dissolve RP and were tested in vitro for plant growth-promoting (PGP) traits including production of indole acetic acid (IAA), siderophores, hydrogen cyanide (HCN), and antifungal activity, as well as their response to the effect of extrinsic and intrinsic stress. The 16S rRNA gene sequencing and phylogenetic analysis identified these isolates belong to four genera, Pantoea, Pseudomonas, Serratia, and Enterobacter. The phosphate solubilization index (SI) of selected isolates ranged between 2.3 and 2.7, and the amount of solubilized phosphorus in the liquid medium varied from 59.1 to 90.2 µg mL−1. HPLC analysis revealed that all the selected isolates produced multiple organic acids (oxalic, citric, gluconic succinic, and fumaric acids) from glucose under aerobic conditions. Except for the A81 strain, all selected isolates were able to produce IAA ranging between 2.9 and 21.2 µg mL−1. The isolates A17, B26, and B107 showed the ability to produce siderophores ranging from 79.3 to 20.8% siderophore units. Only two strains (A17 and B26) were able to produce HCN. All selected isolates showed good resistance against different environmental stresses like 10–50 °C temperature, 0.5–2 g L−1 salt concentration and 4.5–9 pH range, and against different antibiotics. The antagonistic effect showed that among the five selected strains, only two strains (B26 and A17) were able to suppress the growth of tested fungi. This study clearly indicates that our selected rock PSBs can be used as biofertilizers for grain crops after studying their interaction with the host crop and field evaluation.